The present invention relates to clamping bands and more particularly, to a wide clamping band for clamping a connector boot within a hole through a generally cylindrical wall, such as in a pipe-to-manhole connection.
Underground sewer systems typically include a pipe-to-manhole connection 10, FIG. 1. A manhole riser 12, FIG. 2, has a generally cylindrical side wall 14 with at least one opening or hole 16 formed in the side wall 14 either by casting or coring. A pipe 18 extends through the hole 16. The pipe 18 is connected to the manhole riser 12 using a connector boot 20, which is secured to the pipe 18 using an external clamping band 22.
As shown in greater detail in FIG. 3, the connector boot 20 is secured within the hole 16 using an internal clamping band 24. The clamping bands 22, 24 can include conventional expanding/locking mechanisms 26, for example, as disclosed in greater detail in U.S. Pat. Nos. 3,958,313, 5,431,459, 5,738,359, and 5,029,907, all of which are incorporated herein by reference. The pipe 18 and manhole riser 12 are thereby joined together and sealed using the connector boot 20 and clamping bands 22, 24.
In these conventional pipe-to-manhole connections, there has been a limitation on the maximum size of the hole diameter Dh. Prior to the present invention, it was thought that the clamping band 24 must have nearly 100% contact with the inner surface 28 of the hole 16. In other words, the band 24 could not have any overhang inside or outside the hole 16. Thus, it was previously thought that a more narrow band 24 was better in this type of connection.
As shown in greater detail in FIG. 4, the region 29 within which the band 24 can be positioned (with nearly 100% contact) is limited because of the curvature of the generally cylindrical wall 14. For example, a manhole riser having an inner diameter Dl of 48xe2x80x3, and an outer diameter Do of 58xe2x80x3 could have a maximum hole diameter Dh of 28xe2x80x3 allowing a clamping band having a width of about 1.938xe2x80x3. To increase the hole diameter Dh further would decrease the size of the band clamping region 29 to a point where the width of the band is too small to adequately secure the connector boot. Thus, in conventional pipe-to-manhole connections, for each manhole diameter/wall thickness, there is a recommended maximum hole diameter and maximum band size.
Some special connections were developed in an effort to allow a larger hole size. These special connections, however, required special tooling and were often difficult to replace.
Special seals have also been developed to allow for larger hole sizes, for example, compression seals and contour seals such as the types available from A-LOK Products, Inc. and NPC, Inc. These seals also have drawbacks. Compression seals depend on accurate manufacturing tolerances on the pipe utilized in the seal. Changes in pipe OD generally have a large impact on the ease of installation and sealing performance. Compression seals also require specialized manufacturing forms or mandrels. Compression seals further require exact pipe alignment and very high assembly forces (requiring heavy equipment such as back hoes). Contour seals are inflated with water, and specialized pumps are required for installation. Both compression and contour seals will not work with corrugated or ribbed pipes. The curved contours of these seals tend to cross over adjacent ribs creating a leak path.
Accordingly, there is a need for a clamping band capable of being used in a hole within a manhole riser or other generally cylindrical wall at hole diameters in excess of the conventional maximum hole diameter.
The present invention features a connection system comprising a structure having a hole through a generally cylindrical wall of the structure. The hole extends from an outer generally cylindrical surface to an inner generally cylindrical surface of the structure. The connection system also comprises a connector boot having a first end portion and a second end portion with the first end portion extending into the hole in the structure. A clamping band is positioned against an inner boot surface of the first end of the connector boot and applies pressure outwardly to clamp the connector boot against an inner hole surface of the hole. The clamping band has a width such that at least one portion of the clamping band extends beyond the inner hole surface to provide an overhang. Providing a wider clamping band that overhangs is a counter intuitive solution to the problem of securing connector boots in holes having larger diameters
According to a preferred embodiment, at least one portion of the band overhangs the outer generally cylindrical surface of the wall and at least one portion of the band overhangs the inner generally cylindrical surface of the wall. Preferably, about 43% of the clamping band makes contact with the inner hole surface.
The present invention also features a method of connecting a pipe to a structure having a generally cylindrical wall with a hole therethrough, such as a pipe-to-manhole connection. The method comprises the acts of positioning a first end portion of a boot within the hole in the generally cylindrical wall such that at least one portion of the connector boot extends beyond a generally cylindrical inner surface of the wall. The clamping band is then positioned within the first end portion of the connector boot. The clamping band is then expanded and locked against the first end portion of the connector boot to secure the first end portion of the connector boot against an inner hole surface of the hole. At least one portion of the clamping band overhangs the generally cylindrical inner surface and at least one portion of the clamping band overhangs a generally cylindrical outer surface of the wall. The second end portion of the connector boot is then secured to the pipe.
The present invention also features a clamping band comprising a band having a width such that a portion of the band extends beyond an inner hole surface to overhang the inner generally cylindrical surface and a portion of the band extends beyond the inner hole surface to overhang the outer generally cylindrical surface. The clamping band also comprises a band locking mechanism coupled to a band proximate the first and second band ends to lock the band into position.